ECM Hope?

[RobbieAG]

I'm a bit confused after watching all three videos. In the first two, he says the solution is to run another ground wire for the knock sensor circuit so there won't be interference from other circuits, but that the knock sensors would be fully functional. In the last video, he says he decided to bypass the knock sensor circuit all together after explaining how rare it would be to trigger a knock sensor fault.

 

[Andrew Shadow]

he says the solution is to run another ground wire for the knock sensor circuit so there won't be interference from other circuits, but that the knock sensors would be fully functional.

The option if you want to maintain the knock sensor functionality as designed by Honda and avoid developing the code 25/26 fault.
This assumes that this is the cause of the failure and that this cures it.

In the last video, he says he decided to bypass the knock sensor circuit all together after explaining how rare it would be to trigger a knock sensor fault.

The option if you choose to eliminate the knock sensors all together and never want to deal with them again.
The assumption here is that he is correct that pinging is not of any concern and that this will not cause other problems.

A matter of pick your cure, or your poison.

 

[MidLife]

For the effort involved in reviving these ECUs, I may just gut case and install Microsquirtmotherboard and end up with programmable EFI configuration.

Are you saying a MicroSquirt board might fit in the ST ECU case?

Which might simplify interfacing with the ST Harness?

(MicroSquirt may also allow to leave Fuel Cutting off (or retune it) as some have been trying to do for a while, to eliminate throttle snatch...)

Could you reuse some of the mapping Cat tuned with his Bazzaz or would have to start from scratch (and live with default mapping for a while)?

Cost of MicroSquirting may be higher than the current value of my ST....but would still consider!

Value of my ST is only about that of the OEM ECU.....

Blocking off the pair valves and removing the pair solenoid and plumbing smoothed out the idle and lower rpm acceleration curve. And that made it generally easier to create a better performing a/f map. Cheers,,, CAt'

 

[RobbieAG]

The option if you choose to eliminate the knock sensors all together and never want to deal with them again.
The assumption here is that he is correct that pinging is not of any concern and that this will not cause other problems.

I don't see why he thinks that eliminating the knock sensors is a good alternative. At least on the ST1300, it will cause it to go into default mode which is the same as the FI light being on. Maybe the Goldwing is different. That's not really a fix IMO.

 

[rdmnt2002]

Robbie……as Andrew pointed out….the GL guy offers two options….kill the knock sensors by cutting logic wire….or, cut the logic wire AND add a dedicated ground wire, which restores the knock circuit.

 

[Andrew Shadow]

At least on the ST1300, it will cause it to go into default mod

That is an often made remark. I am not convinced that this is the case with this particular failure. Not every failure that sets a fault code results in limp mode operation in every fuel injection system. The Honda service manual does not state that this is the case for code 25/26.

My thought is that any failure that triggers a fault code 25/26 causes the loss of dynamic ignition timing advance adjustment, which results in less timing advance, which results in less power and increased fuel consumption. The loss of power that is felt is then attributed to being operated in limp mode.

Huge caveat regarding the above- I have no expert knowledge of this particular system. l base the above on extrapolation from my knowledge of automobile fuel injection systems of the same era.

It would certainly be helpful to have more complete technical information from Honda, but that isn't going to happen.

 

[aniwack]

We are accepting faulty ECU's on this thread for study and possible repair:

Wanted - Code 25/26 ECU's | Buy/Sell/Wanted

Do you have a Code 25/26 ECU laying around that we can send to the lab? Drop me a PM! [Mellow don't delete this.] {{don't tell me what to do lol}} [[I do what I want lmao]]

www.st-owners.com

 

[RobbieAG]

That is an often made remark. I am not convinced that this is the case with this particular failure. Not every failure that sets a fault code results in limp mode operation in every fuel injection system. The Honda service manual does not state that this is the case for code 25/26.

My thought is that any failure that triggers a fault code 25/26 causes the loss of dynamic ignition timing advance adjustment, which results in less timing advance, which results in less power and increased fuel consumption. The loss of power that is felt is then attributed to being operated in limp mode.

I wouldn't describe the 1300's default mode as "limp mode". I notice very little if any loss of power, but do see a loss of fuel economy. The FSM lists the symptoms for codes 25 and 26 as, "Engine operates normally". I agree it isn't setting ignition advance normally though.

 

[ASPC]

The new ECM I purchased from Ron Ayers for my 07 had a pin missing when compared to the old ECM. I don’t remember which pin it was or if it was related. I have the old ECM partially stripped down. I’m not especially interested in this subject. But it became more important when they stopped making them.

I don’t think the ECM uses the knock sensors to control engine timing or fuel air ratio. In theory I think they could be disconnected but I wouldn’t feel comfortable doing that.

I know the knock sensors work on my bike because one time I was in a town and pulled away in 3rd at some lights and she knocked and the FI light came on and immediately went off when I pulled in the clutch.

The ECM is not modifying the fuel air ratio or the ignition timing by listening for knock. That is already permanently mapped out inside the ECM. The knock sensor circuit is a fail safe incase something goes wrong with the engine or the fuel. This is the normal method of ECM programming and function.

The biggest problem is that this is a complex subject and most people do not have any real understanding of how ECMs work. It’s not worth arguing about. This may as well be an oil or suspension thread, pointless.

Read up on engine control mapping.

 

[tnbill]

Let the fun begin

 

[W0QNX]

Interseting. Lot's to think about on the ecm issue. His conclusion at the last is most interesting.

 

[DannoXYZ]

This is straight from Honda document ©2006 explaining how their PGM-FI system works. I extracted only pages dealing with knock-sensor, hopefully not enough to alert Honda's attourneys. Doesn't mention ST specifically, does have similar GL1800. I assume programming is same for pretty much all their bikes. With differences in values stored data-tables for various parameters.

 

[Andrew Shadow]

I don’t think the ECM uses the knock sensors to control engine timing

The ECM is not modifying the ignition timing by listening for knock.

This is exactly what the purpose of the knock sensors is and what happens. The knock sensor detects detonation and sends a signal to the ECM which retards ignition timing until the knock sensor stops sending the signal.

The introduction of knock sensor is what has allowed much more timing advance without causing engine damage as well as allowing for constant dynamic control of ignition timing advance. The ECM constantly advances the timing within it programmed parameters until detonation is detected, then it retards it until it isn't detected to find the sweet spot of maximum possible timing advance without causing engine damage under all conditions.

As a quick check of the system while I had a scanner connected to a vehicle I would tap the area around the knock sensor with a steel hammer. With every wrap of the hammer I would watch as the timing was being retarded by the ECM in response to what the knock sensor was detecting.

 

[DannoXYZ]

On last page, you see "MAX ADVANCED IGNITION TIMING". This value is derived from using TPS x RPM look-up points on 3D ignition map. From different Honda, but similar pattern with map. Higher advance at lower loads and RPMs. With more as RPMs increase and less as loads increase. Far left rear at bottom of map Iowest load & RPM: idle.

These are ignition-advance values ECU starts with. Then if it detects knock, it retards ignition below these pre-programmed values. Knock-detection is an extreme safety measure, not performance feature. At no time will ECU ever use more ignition-advance than what's programmed in these maps. AND, they have huge safety margin. Easily 6-8 degrees away from edge of knocking on 87-oct. PON/AKI petrol and 10-12 degrees using 91-oct. Pretty much any bike or auto manufacturer programs ignition maps far, far away from detonation edge with extra petrol under WOT for safety. Just in case you get bad petrol out in boonies on super-hot day. Or your fuel-pump starts failing or fuel-filtre or injectors clogs. This safe ignition & fuel maps allows for failures to occur and not destroy engine.

That's where dyno-tuning easily unlocks 5% more power on any bike by just adding more ignition-advance and leaning out mixtures to most-powerful 13.5:1 AFR. Usually on highest-load/high-RPM WOT areas of map where max-power is generated.

Reason they don't have programming closer to ragged-edge is because knock-sensors aren't sure thing. Filtering out noise sometimes hides detonation as well. And at high-RPMs, there's so much valvetrain noise, that detecting knock is difficult and unreliable.

I've found best knock-detector is between my ears. Human brain's pattern-recognition ability is way, way better than any computer at the moment. I use one of these with headphones when tuning on dyno. I'll add extra ignition-advance and lean out mixtures gradually. And listen for knock during each dyno-run. I can pick up knock before ECU flags it. Then I back off a couple of degrees ignition for safety.

https://linkecu.com/tech-articles/knockblock-explained/

 

[Chris09]

That's an insane amount of timing advance; as high as 64 degrees. I was about to ask if the graph with the grey zone could be real, but I remember reading a statement that the knock circuit could reduce advance by 38 degrees which I thought how could that even be possible.
This answers one question for me at least, regarding the problem as it pertains to the blackbird, there's a guy that claims to achieve equal dyno readings with or without the fault set. What you're showing is that the knock circuitry timing advance control only functions within a portion of the rpm range, and can potentially sharply drop at the high end to have no effect by about 85% of WOT, so at redline it's out of the loop anyway. I'll have to go back and see if he posted or has the charts, maybe they could be overlayed for comparison. I'd expect from this that horsepower and torque would be compromised through the knock sensor range, then track about equally to peak horsepower. It would be interesting to see to what extent that change exists, my guess would be it's most significant at lower rpm / throttle position, but I'm not a good guesser. This is very interesting.

 

[DannoXYZ]

Sorry, I should’ve mentioned this was from different model Honda. That’s ignition-advance with engine free-revving in neutral. Looks like inefficient 2-valve map huh? Per-gear ignition maps have much less advance due to higher loads.

I did find dyno-chart of Blackbird with code set and it lost about 10-15% peak power/torque. I suspect that there’s fixed amout of ignition retard across board when code is triggered. From amount of lost power, I’d say it’s about 7-8 degrees in high-end. Note that in this doc, result of code 25 is “Poor engine performance” triggered by “No signal input though engine RPM is higher than a specified speed” (4000rpm?). Which matches many people’s experience in discovering melted and frayed wiring. Extra noise picked up from other areas of harness may contribute as well.

Similar to O2-sensor, knock-sensor isn’t as useful at high-RPMs and high-loads due to noise. Even with sophisticated dedicated computer for detecting knock and managing ignition-retard, there were plenty of Porsche Turbos showing up at my shop with blown headgaskets.

These were always caused by modifying away from factory configuraton: increased boost, extra ignition advance without appropriate increase in octane. The knock computer can only do so much; designed for worse-case scenario with stock config. When you modify things to point where detonation is common occurance, it can’t be depended on to save you from tuning mistakes.

 

[DannoXYZ]

That's an insane amount of timing advance; as high as 64 degrees. I was about to ask if the graph with the grey zone could be real, but I remember reading a statement that the knock circuit could reduce advance by 38 degrees which I thought how could that even be possible.
This answers one question for me at least, regarding the problem as it pertains to the blackbird, there's a guy that claims to achieve equal dyno readings with or without the fault set. What you're showing is that the knock circuitry timing advance control only functions within a portion of the rpm range, and can potentially sharply drop at the high end to have no effect by about 85% of WOT, so at redline it's out of the loop anyway. I'll have to go back and see if he posted or has the charts, maybe they could be overlayed for comparison. I'd expect from this that horsepower and torque would be compromised through the knock sensor range, then track about equally to peak horsepower. It would be interesting to see to what extent that change exists, my guess would be it's most significant at lower rpm / throttle position, but I'm not a good guesser. This is very interesting.

For reference, here's ignition-map from my '07 CBR600RR. Under 100% WOT at 6400rpms, it's using 55-degrees of advance!

Interesting feature is valley on left side of map at idle-speed, 1400rpms (green). Notice at lower-RPMs than that, there's an increase in ignition-advance? That's to "funnel" engine-speed back up to 1400rpms if it drops below that. Kinda like idle-stabilizer valve for air, but using ignition-timing.

 

[ASPC]

This is exactly what the purpose of the knock sensors is and what happens. The knock sensor detects detonation and sends a signal to the ECM which retards ignition timing until the knock sensor stops sending the signal.

The introduction of knock sensor is what has allowed much more timing advance without causing engine damage as well as allowing for constant dynamic control of ignition timing advance. The ECM constantly advances the timing within it programmed parameters until detonation is detected, then it retards it until it isn't detected to find the sweet spot of maximum possible timing advance without causing engine damage under all conditions.

As a quick check of the system while I had a scanner connected to a vehicle I would tap the area around the knock sensor with a steel hammer. With every wrap of the hammer I would watch as the timing was being retarded by the ECM in response to what the knock sensor was detecting.

Yes, the ECM detected a problem and retarded the ignition, as it is designed to do. But it does not use the knock sensor to push the ignition timing, that is already written on a map.

 

[Andrew Shadow]

Yes, the ECM detected a problem and retarded the ignition, as it is designed to do.

The ECM can not do that without the knock sensors. Just like a human brain can not feel pain, the ECM can not detect detonation, it can only react once it has been advised of its presence. It is the knock sensor that detects this problem and advises the ECM by sending a signal to the it. The ECM then uses that data to know how much to retard the timing.

But it does not use the knock sensor to push the ignition timing, that is already written on a map.

If by push you mean advancing the ignition timing, I did not state that the ECM uses the knock sensor to advance the timing. Quite the contrary, I wrote that the ECM advances the timing, and that it uses the data provided by the knock sensor to retard the timing.

 

[DannoXYZ]

The ECM can not do that without the knock sensors. Just like a human brain can not feel pain, the ECM can not detect detonation, it can only react once it has been advised of its presence. It is the knock sensor that detects this problem and advises the ECM by sending a signal to the it. The ECM then uses that data to know how much to retard the timing.

If by push you mean advancing the ignition timing, I did not state that the ECM uses the knock sensor to advance the timing. Quite the contrary, I wrote that the ECM advances the timing, and that it uses the data provided by the knock sensor to retard the timing.

ECM never advances timing. Only starts with what’s programmed in maps. Then retards from there if knock is detected. This dithering always results in ignition-advance values lower than pre-programmed map values.